Nerve Injuries Flashcards
List the layers of a nerve from axon to peripheral nerve.
Axon Myelin sheath (neruolemma) Endoneurium = nerve fiber Perineurium = fascicle (multiple nerve fibres) Epineurium (peripheral nerve)
What is a neuroma?
Bundle of nerves which is painful
What are the consequences of a nerve injury?
Loss of function - motor, sensory and proprioception
Neuroma formation
How do you describe the grades of nerve injury?
Using Seddon’s classification
What are the grades in Seddon’s classification?
Class I-III
- Neurapraxia
- Axonotmesis
- Neurotmesis
What is a grade I nerve injury?
Neurapraxia
It is a conduction block without loss of axonal continuity. In neuropraxia, there is a physiologic block of nerve conduction in the affected axons.
What is a grade II nerve injury?
Axonotmesis - It involves loss of the relative continuity of the axon and its covering of myelin, but preservation of the connective tissue framework of the nerve (the encapsulating tissue, the epineurium and perineurium, are preserved). Axon can regenerate.
What is a grade III nerve injury?
Neurotmesis - It is a total severance or disruption of the entire nerve finer. A peripheral nerve fiber contains an axon (Or long dendrite), myelin sheath (if existence), their schwann cells, and the endoneurium. Neurotmesis may be partial or complete. Potential of growth is very unpredictable.
What are the stages of Sunderland’s classification of nerve injury?
I = Neuropraxia II = Axonotmesis III = Axonal and endoneurial disruption IV = Perineurial rupture and fascicle disruption V = Neurotmesis (nerve trunk discontinuity)
Which nerves supply the lower limbs?
- Femoral nerve and branches
- Sciatic nerve and branches
- Obturator nerve
- Superior gluteal nerve
What are the causes of neuropathy?
Injury-stretch of nerve, complete division
Extrinsic pressures: tumour, abscess etc
Medical conditions (diabetes, alcohol, drugs)
Rare causes: nerve tumour
What is piriformis syndrome?
- Sciatica symptoms not originating from spinal roots and/or spinal disc compression but involving the overlying piriformis muscle
- Overuse of muscle leads to spasm
- Diagnosis of exclusion and treatment is mostly about activity modification
What is meralgia paraesthetica?
- Compression of the nerve as it passes through the inguinal ligament or as it pierces the fascia lata causes include obesity (compression of abdominal fat), pregnancy, tight clothing etc
- Burning or stinging sensation in the distribution of the nerve over the anterolateral aspect of the thigh.
- This is aggravated by walking or standing and received by lying down with the hip flexed
- Diagnosis is confirmed by the absence of motor signs and excluding pelvic and intra-abdominal causes of irritation e.g. tumour
What are the causes of injury to the superficial perineal nerve?
- Ankle surgery via a lateral approach
- Ankle arthroscopy portal placement
What are the consequences of a tibial nerve injury?
- Loss of the posterior leg compartments (gastrocnemius, tibialis posterior, long flexors)
- Weakness in plantar flexion and inversion
- Loss of plantar sensation except medial and lateral sides supplied by saphenous and sural nerves
- Unopposed pull of dorsiflexors and reverters
- Clcoaneovalgus foot
